CVE-2026-51663 in TOTOLINK
Summary
by MITRE • 08/29/2026
Incorrect access control in the getWiFiApcliScan function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to trigger wireless scans and retrieve AP-client scan results via sending a crafted POST request to /cgi-bin/cstecgi.cgi.
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Analysis
by VulDB Data Team • 08/29/2026
The vulnerability identified in TOTOLINK T6 router firmware version 4.1.5cu.748_B20211015 represents a critical failure in access control mechanisms within the device's web management interface. Specifically, the flaw resides in the getWiFiApcliScan function, which is exposed through the Common Gateway Interface script located at /cgi-bin/cstecgi.cgi. This architectural design allows external actors to interact with internal network scanning utilities without requiring valid authentication credentials. The absence of proper authorization checks means that any entity capable of reaching the router's web server can invoke this functionality remotely.
From a technical perspective, an unauthenticated attacker can exploit this weakness by sending a specifically crafted POST request to the targeted CGI endpoint. Upon receiving this malicious payload, the vulnerable function executes a wireless scan operation on behalf of the requester and subsequently returns the results directly in the HTTP response body. This behavior effectively bypasses standard security controls designed to restrict administrative functions to authenticated users only. The exploitation does not require complex privilege escalation or prior foothold within the network; it relies solely on network reachability to the management interface, which is often exposed via default configurations where remote administration may be enabled or accessible from adjacent untrusted networks if NAT rules are misconfigured.
The operational impact of this vulnerability extends beyond simple information disclosure. By retrieving AP-client scan results, an attacker gains detailed visibility into the surrounding wireless environment. This includes a list of nearby access points, their MAC addresses, signal strengths, and potentially connected client devices depending on the depth of data returned by the firmware implementation. Such intelligence is highly valuable for conducting targeted attacks against other network participants. For instance, knowledge of specific SSIDs and associated clients can facilitate deauthentication attacks, rogue access point deployment, or man-in-the-middle positioning strategies aimed at intercepting traffic from vulnerable users within range.
This vulnerability aligns with CWE-284, which describes Improper Access Control, as the system fails to enforce appropriate restrictions on authenticated users' ability to perform actions. Furthermore, it maps to MITRE ATT&CK technique T1046, Network Service Discovery, specifically under wireless scanning sub-tactics used for reconnaissance and mapping of network topology. The exploitation vector is classified as remote with no additional prerequisites other than network connectivity, significantly lowering the barrier to entry for malicious actors compared to vulnerabilities requiring local access or user interaction.
Mitigation strategies should prioritize immediate patching if a vendor-provided firmware update addressing this specific flaw is available. In cases where updating is not immediately feasible, administrators must ensure that remote management interfaces are disabled unless absolutely necessary. If remote access is required, it should be restricted through strict IP whitelisting using firewall rules to limit exposure only to trusted source addresses. Additionally, changing the default administrative credentials and disabling unused services such as UPnP can reduce the overall attack surface. Regular security audits of router configurations against industry best practices are essential to prevent similar misconfigurations that expose internal functions to unauthenticated external access.